2 Level 8 DARK monsters

Must be Xyz Summoned and cannot be Special Summoned by other ways. Once per turn, during either player's turn: You can detach 1 Xyz Material from this card and send 1 card from your hand to the Graveyard, then target 1 face-up card your opponent controls; change this card to Defense Position, and if you do, that face-up card has its effects negated until the end of this turn.